Hey so during the papyrus fight, he never kills you. So it seems he knows your health. When fighting Toriel, she fights you with no intention to kill you, but ends up doing so and regrets it with the frame that shows her shocked face. Do you think theres anything behind this, or am I overthinking? Its been rattling around my head for a wild. Sorry to bother you, have a nice day!
It’s not a bother at all, we love questions!
So, let us see. With Papyrus, there is one very specific difference between him and a lot of other monsters:
Papyrus’ intention throughout Snowdin is to capture a human. While his behavior is very affable and he certainly looks enthusiastic, but harmless, there’s a lot more to him. Not only does Undyne admit he’s pretty tough, but while hanging out with him, he also alludes to the fact that he could have blasted Frisk.
However, that’s not what he wants. Although he ultimately does try to use his special attack, it’s after numerous warnings and delays.
YEAH! DON’T MAKE ME USE MY SPECIAL ATTACK!
I CAN ALMOST TASTE MY FUTURE POPULARITY!!!
PAPYRUS: HEAD OF THE ROYAL GUARD!
PAPYRUS: UNPARALLELED SPAGHETTORE!
UNDYNE WILL BE REALLY PROUD OF ME!!
THE KING WILL TRIM A HEDGE IN THE SHAPE OF MY SMILE!!!
MY BROTHER WILL … WELL, HE WON’T CHANGE VERY MUCH.
I’LL HAVE LOTS OF ADMIRERS!! BUT…
HOW WILL I KNOW IF PEOPLE SINCERELY LIKE ME???
WILL ANYONE LIKE ME AS SINCERELY AS YOU?
SOMEONE LIKE YOU IS REALLY RARE…
I DON’T THINK THEY’LL LET YOU GO…
AND DATING MIGHT BE KIND OF HARD…
AFTER YOU’RE CAPTURED AND SENT AWAY.
URGH… WHO CARES! GIVE UP!!
GIVE UP OR FACE MY… SPECIAL ATTACK!!!
YEAH!!! VERY SOON I WILL USE MY SPECIAL ATTACK!
NOT TOO LONG AND I WILL USE THAT SPECIAL ATTACK!!!
THIS IS YOUR LAST CHANCE… BEFORE MY SPECIAL ATTACK!!
His goal is above all else is to prove himself and join the Royal Guard, making his special attack a last ditch effort to defeat and capture the human. To that end, he can’t let Frisk die. More so than other monsters, Papyrus displays a very keen understanding of just how much punishment the human can take. Not to mention he’s significantly more concerned with making friends, and Frisk proves to be friend for him.
Now, Toriel is a very different case. By the time she opposes Frisk, six fallen have already left her care and perished. As far as Toriel is concerned, they could easily become the seventh. Stopping Frisk from leaving the Ruins is not just to protect them, but to prevent Asgore’s ascension to godhood.
Dying to Toriel isn’t exactly the easiest feat. When Frisk is down to 2 HP, only a single attack is repeated and initiated in a way that cannot be exploited. You can’t intentionally die against Papyrus, but you can against Toriel and a lot of this may have to do with their attitude towards the encounter.
Papyrus is absolutely set on capturing the human and everything he does during the fight serve that purpose, along with a little bit of showing off near the end. However, Toriel is different. She doesn’t actually want to fight Frisk and even during the encounter, she does her best to disassociate from what’s happening, wanting them to just accept her reasons and return to their room. Her fight is slightly more about intimidation, that trying to actively harm Frisk.
This reflects in the fight as well. If Frisk dies to her, the resulting look on her face for that one frame before the SOUL shatters, is one of clear shock. It was never her intention, but in all her turmoil, she didn’t make completely sure.
Unfortunately, that one slip is just enough for tragedy to strike.